This invention relates generally to gas turbine engines, and more specifically to gas turbine engine assemblies and methods of assembling the same.
At least some known gas turbine engines include a forward fan, a core engine, and a power turbine. The core engine includes at least one compressor, a combustor, a high-pressure turbine, and a low-pressure turbine coupled together in a serial flow relationship. More specifically, the compressor and high-pressure turbine are coupled through a shaft to define a high-pressure rotor assembly. Air entering the core engine is then mixed with fuel and ignited to form a high energy gas stream. The gas stream flows through the high-pressure turbine, rotatably driving it, such that the shaft that, in turn, rotatably drives the compressor.
The gas stream expands as it flows through the low-pressure turbine. The low-pressure turbine rotatably drives the fan through a low-pressure shaft such that a low-pressure rotor assembly is defined by the fan, the low-pressure shaft, and the low-pressure turbine. To facilitate increasing engine efficiency, at least one known gas turbine engine includes a counter-rotating low-pressure turbine that is coupled to a counter-rotating fan and/or a counter-rotating booster compressor.
To assemble a gas turbine engine including a counter-rotating low-pressure turbine, an outer rotating spool, a rotating frame, a mid-turbine frame, and two concentric shafts, are installed within the gas turbine engine to facilitate supporting the counter-rotating turbine. The installation of the aforementioned components also enables a first fan assembly to be coupled to a first turbine and a second fan assembly to be coupled to a second turbine such that the first and second fan assemblies each rotate in the same rotational direction as the first and second turbines. Accordingly, the overall weight, design complexity, and/or manufacturing costs of such an engine are increased.